The present invention relates to a laser source device for emitting a laser beam, an image display device equipped with the laser source device, and a monitor device.
In recent years, a laser source device is widely used in the opto-electronics field such as an optical communication, an optical application measurement, or an optical display.
As such laser source devices, there are cited those applying the wavelength of the fundamental laser without modification and those applying the wavelength of the fundamental laser with modification. In the latter laser source devices, a second harmonic generation (SHG) element is known as an element for performing wavelength conversion of the fundamental laser.
Here, since the conversion efficiency of the SHG is generally around a few %, the power of the light converted by the SHG element is substantially reduced in comparison with the power of the output light of the fundamental laser source. Therefore, as a configuration for suppressing the power reduction of the output light, there is proposed a laser source device as in a patent document 1. In the laser source device, a light beam emitted from an internal resonance type of laser source and transmitted through the SHG element is separated into a first SHG light beam having a converted wave length and a residual fundamental light beam. Then, the residual fundamental light beam is led through the SHG element again, thereby taking out a second SHG light beam having a converted wavelength. The second SHG light beam is combined with the first SHG light beam in a condition in which the second SHG light beam is converted into a polarized light beam having a polarization direction 90° different from the first SHG light beam. In the laser source device of the patent document 1, by thus utilizing the composite light beam of the first SHG light beam and the second SHG light beam as the output light, the power reduction of the output light beam is suppressed.
[Patent Document 1] JP-A-59-128525 the third official gazette